When a full Vest if too bulky, and when your arms get too tired from flying, an arm brace can sure come in handy. If you're not a DIY type of guy/gal, then your other option for a forearm brace is the bulkier Flycam version (below).

Flycam Forearm Arm Brace for Flycam and Glidecam HD Stabilizer

Something like this new Skyler MiniArm is most likely not going to be comfortable with your large Glidecam setups, but for all the new mini handheld stabilizers popping up and pocket cinema cameras, it should do well to provide arm strain relief.

@Paul - The design of the Skyler (or similar) works on the principles of the 'Glidecam Style' stabilizer. Personally, I find these easier to fly than the Merlin which is why I preferred even the Flycam over the Merlin.